The present invention relates to audio amplifiers and more particularly to class D audio amplifiers.
It is known to use power semiconductor devices in audio amplifier circuits. It is also well known that the characteristics of the power semiconductor device used in the amplifier circuit affects the performance of the circuit. Yet, in many amplifier applications, the negative effects due to the performance of the power semiconductor devices are alleviated by extraneous circuit elements. Such measures lead to the increase in the cost of the amplifier circuit as well as its physical size.
Furthermore, the power semiconductor devices used in prior art circuits as conventionally packaged introduce parasitic parameters such as package related parasitic inductance, resistance, and thermal characteristics.
According to the present invention a power semiconductor device such as a power MOSFET is tuned to be used in a class D amplifier assembly. That is, the characteristics of the power semiconductor device have been optimized for a class D audio amplifier.
In addition, the power semiconductor device, which has been tuned for a class D audio amplifier application, is disposed in a conductive clip and integrated within the amplifier circuit without the use of wirebonds. It has been found that the conductive clip can make a package according to the present invention particularly suitable for class D amplifiers. Specifically, the use of the conductive clip enhances performance in class D audio amplifier circuits by reducing inductance, improving switching characteristics and electromagnetic interference (EMI) rejection. Furthermore, thermal efficiency resulting from the use of the conductive clip enables 100 W operation into 8 ohms without a heatsink. Advantageously, eliminating the heatsink shrinks circuit size and bulk, giving designers more layout flexibility. Such a package is most suitable for use in medium power class D audio amplifier where the electrical characteristics, small size and improved thermal conduction offered by the device result in improved audio performance factors such as efficiency, EMI, and power density.
Such a package preferably has an Rg maximum guarantee for better dead time control, which is an important factor related to THD performance in class-D amplifiers.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.